Relief valves are used to control or limit the pressure in a system or vessel which can build up in the vessel. In particular, relief valves are used on containers such as cryogenic cylinders containing industrial cryogenic liquids (Nitrogen, Argon, Oxygen, etc.) to allow pressurized gas built up in the container to flow out from the relief valve. This may help to prevent failure of the container. Cryogenic liquids stored in containers pose a particular challenge because pressure is always building in the container as the cryogenic temperature is around −295° F. It follows that relief valves can be found installed onto such containers to release gas pressure.
Containers stored or installed indoors, such as at research facilities and hospitals, present an additional problem as the release of pressure from the relief valve can be noisy. When this takes place in a laboratory setting, for example, where delicate work is being conducted, the noise can disrupt the working environment. Further, current Occupational Safety and Health Administration (OSHA) requirements state that a permissible exposure limit is 90 decibels for an 8-hour shift; any exposure over this limit requires hearing protection. In addition, for each increase of 5 decibels above the 90-decibel limit, the exposure time is cut in half. Thus, a valve which can effectively relieve pressure in a pressurized container while reducing the discharging noise is desirable.